Re: [syzbot] WARNING in hugetlb_change_protection

[Mike Kravetz]

I'll start looking at this, but adding Peter this may be related to his
recent changes.
-- 
Mike Kravetz

On 08/03/22 08:32, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    e65c6a46df94 Merge tag 'drm-fixes-2022-07-30' of git://ano..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=139cc282080000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=26034e6fe0075dad
> dashboard link: https://syzkaller.appspot.com/bug?extid=824e71311e757a9689ff
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> userspace arch: i386
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+824e71311e757a9689ff@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 28745 at include/linux/swapops.h:319 make_pte_marker_entry include/linux/swapops.h:319 [inline]
> WARNING: CPU: 1 PID: 28745 at include/linux/swapops.h:319 make_pte_marker include/linux/swapops.h:342 [inline]
> WARNING: CPU: 1 PID: 28745 at include/linux/swapops.h:319 hugetlb_change_protection+0xf85/0x1610 mm/hugetlb.c:6392
> Modules linked in:
> CPU: 1 PID: 28745 Comm: syz-executor.3 Not tainted 5.19.0-rc8-syzkaller-00146-ge65c6a46df94 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
> RIP: 0010:make_pte_marker_entry include/linux/swapops.h:319 [inline]
> RIP: 0010:make_pte_marker include/linux/swapops.h:342 [inline]
> RIP: 0010:hugetlb_change_protection+0xf85/0x1610 mm/hugetlb.c:6392
> Code: e8 d0 5a b7 ff 0f b6 94 24 80 00 00 00 48 8b 84 24 98 00 00 00 84 d2 0f 84 ef 02 00 00 49 89 c4 e9 48 fb ff ff e8 ab 5e b7 ff <0f> 0b 48 b9 00 00 00 00 00 fc ff df 48 89 d8 48 c1 e8 03 80 3c 08
> RSP: 0018:ffffc90014cc7780 EFLAGS: 00010212
> RAX: 000000000000082a RBX: ffff88807750e820 RCX: ffffc90006723000
> RDX: 0000000000040000 RSI: ffffffff81c30c25 RDI: 0000000000000007
> RBP: ffff888074de5ea0 R08: 0000000000000007 R09: 0000000000000000
> R10: 0000000000000004 R11: 0000000000000001 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000004 R15: ffff88801fcc8e00
> FS:  0000000000000000(0000) GS:ffff8880b9b00000(0063) knlGS:00000000f7f06b40
> CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
> CR2: 0000000020000040 CR3: 000000001b84c000 CR4: 00000000003526e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  change_protection+0x96b/0x3ad0 mm/mprotect.c:463
>  mwriteprotect_range+0x387/0x5c0 mm/userfaultfd.c:759
>  userfaultfd_writeprotect fs/userfaultfd.c:1823 [inline]
>  userfaultfd_ioctl+0x438/0x4340 fs/userfaultfd.c:1997
>  compat_ptr_ioctl+0x67/0x90 fs/ioctl.c:906
>  __do_compat_sys_ioctl+0x1c7/0x290 fs/ioctl.c:968
>  do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
>  __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
>  do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203
>  entry_SYSENTER_compat_after_hwframe+0x70/0x82
> RIP: 0023:0xf7f0b549
> Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
> RSP: 002b:00000000f7f065cc EFLAGS: 00000296 ORIG_RAX: 0000000000000036
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000c018aa06
> RDX: 00000000200000c0 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>  </TASK>
> ----------------
> Code disassembly (best guess):
>    0:	03 74 c0 01          	add    0x1(%rax,%rax,8),%esi
>    4:	10 05 03 74 b8 01    	adc    %al,0x1b87403(%rip)        # 0x1b8740d
>    a:	10 06                	adc    %al,(%rsi)
>    c:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
>   10:	10 07                	adc    %al,(%rdi)
>   12:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
>   16:	10 08                	adc    %cl,(%rax)
>   18:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
>   1c:	00 00                	add    %al,(%rax)
>   1e:	00 00                	add    %al,(%rax)
>   20:	00 51 52             	add    %dl,0x52(%rcx)
>   23:	55                   	push   %rbp
>   24:	89 e5                	mov    %esp,%ebp
>   26:	0f 34                	sysenter
>   28:	cd 80                	int    $0x80
> * 2a:	5d                   	pop    %rbp <-- trapping instruction
>   2b:	5a                   	pop    %rdx
>   2c:	59                   	pop    %rcx
>   2d:	c3                   	retq
>   2e:	90                   	nop
>   2f:	90                   	nop
>   30:	90                   	nop
>   31:	90                   	nop
>   32:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
>   39:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
> 
> 
> ---
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> 
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